cranial nerves

1. CRANIAL NERVES
Presented by : DR. MITALI .V. THAMKE
I M.D.S

2. INDEX
• Introduction
• Cranial nerves
• Olfactory (CN I)
• Optic (CN II)
• Oculomotor (CN III)
• Trochlear (CN IV)
• Trigeminal (CN V)
• Abducent (CN VI)
• Facial (CN VII)
• Vestibulocochlear (CN IIIV)
• Glossopharyngeal (CN IX)
• Vagus (CN X)
• Spinal Accessory (CN XI)
• Hypoglossal (CN XII)
• Conclusion
• References

3. INTRODUCTION
• The nervous system is one of the most complex but the
chief controlling system of the body.
• It carries information through sensory impulses to the
brain; process it store it and carries the command to
the effector organ through the motor impulses.

4. THE
NERVOUS
SYSTEM
THE
CENTRAL
NERVOUS
SYSTEM
THE
PERIPHERAL
NERVOUS
SYSTEM
THE
AUTONOMIC
NERVOUS
SYSTEM

5. CENTRAL NERVOUS SYSTEM
1.BRAIN-The chief control center.
2.SPINAL CORD- Conducts sensory information from
peripheral nervous system to the brain.
Conducts motor information from brain to various
effectors.

6. PERIPHERAL NERVOUS
SYSTEM
• It is located outside the central nervous system.
• It comprises of SOMATIC NERVOUS SYSTEM and
innervates the voluntary muscles of the body.
• It consists of 12 pairs of Cranial nerves and 31 pairs of
Spinal nerves

7. AUTONOMIC
NERVOUS SYSTEM
-Strictly motor in nature.
-It controls involuntary activities
and innervates involuntary
muscles.
It is further divided into two types:
-Parasympathetic nervous
system.
-Sympathetic nervous system.

8. TERMINOLOGIES
• NEURON:
It is the structural and
functional unit of the
nervous system.
It consists of cell body and
other processes.

9. Classification of neurons
ACCORDING TO THE NUMBER OF NEURONS:
• Unipolar Neurons-Mesencephalic nucleus of Vth nerve.
• Bipolar Neurons-First neuron of Retina.
• Multipolar Neurons-All motor neurons.
• Pseudounipolar Neurons-Sensory Ganglia of the cranial nerve.

10. • Nucleus:An aggregate
of cell bodies located
within the Central
Nervous System.
• Ganglia:It is the group
of nerve cell bodies
located outside the
Brain and spinal cord.

11. • Tract: It is a group of nerve cell
processes within the central
nervous system.
• Plexus: It is the site of
intermingling and regrouping of
peripheral nerves derived from
diverse origins.
Nerve: Is a bundle of neuronal process
outside the central nervous
system.
1. Sensory nerves
2. Motor nerves
3. Mixed nerves.

12. • Visceral Nerves: They are the nerves which supply the
different viscera, the organs within the body cavity.
They are better known as autonomic nerves.
• Somatic nerves: They supply somatic structures (skin
and muscles).
• General : Refers to stimuli conducted throughout the
entire body, common to both cranial and spinal nerves.
eg. touch, pressure, vibration, pain and proprioception.
• Special : Afferent impulses are encoded by highly
specific sense organs and transmitted to the brain in
certain cranial nerves. eg. Olfaction, vision, taste,
hearing and vestibular function.

13. • Afferent nerves: these fibres bring information from the
periphery to the central nervous system and from one
part of the central nervous system to another.All nerves
are sensory.
• Efferent nerves: carry commands to specific organs or
they carry command from one part of the central
nervous system to another .All nerves are motor in
nature.

14. Embryological
development

15. • The entire nervous system is of ectodermal origin.
• During the 4th week after fertilization ,a process of neural plate
formation and its infolding to form neural tube.
• During neurulation embryo is referred to as neurula.

16. Pharyngeal arch Associated
cranial nerve
Muscles
supplied
1st Arch Maxillary and
Mandibular branches
of trigeminal nerve
Muscles of
Mastication,anterior
belly of Digastric
2nd Arch Facial nerve Muscles of facial
expression ,posterior
belly of digastric
3rd Arch Glossopharyngeal
nerve
Stylopharyngeus
4th Arch Superior Laryngeal
branch of Xth nerve
Cricothyroid
6th Arch Recurrent Laryngeal
branch of Xth nerve
Muscles of Larynx
except Cricothyroid

17. The Cranial nerves

18. • Cranial nerves are bundles of sensory or motor fibers that
innervate muscles or glands; carry impulses from sensory
receptors, or show a combination of these fiber types.
• They are called cranial nerves because they emerge
foramina or fissures in the cranium and are covered by
tubular sheaths derived from the cranial meninges.
• There are twelve pairs of cranial nerves, which are
I to XII, from rostral to caudal, according to their attachment
to the brain and penetration of the cranial dura. Their
reflect their general distribution or function.

19. CRANIAL NERVES
• Olfactory (I)
• Sensory (smell)
13-24
• Optic (II)
– Sensory (sight)
• Oculomotor (III)
– Motor (4 of 6 eye
muscles)
– Parasympathetic
(constriction of pupil,
movement of lens)

20. CRANIAL NERVES
• Trochlear (IV)
• Motor (1 eye
muscle)
13-25
• Trigeminal (V)
– Sensory (face, nasal
cavity, cheeks, lips, skin of
mandible)
–Motor (muscles of
mastication, anterior belly
of digastric, mylohyoid)
• Abducens (VI)
– Motor (1 eye muscle)

21. CRANIAL NERVES
• Facial (VII)
• Sensory (taste)
• Motor (facial
muscles, posterior
belly of digastric)
• Parasympathetic
(salivary glands,
glands of nasal
cavity)
13-26
• Vestibulocochlear (VIII)
– Sensory (hearing and
balance)
• Glossopharyngeal (IX)
– Sensory (taste, back of
mouth, tonsils, middle ear)
– Motor (1 muscle of
pharynx)
– Parasympathetic (salivary
gland, glands of tongue)

22. CRANIAL NERVES
• Vagus (X)
• Sensory (taste, back of
mouth, larynx, thoracic
and abdominal organs)
• Motor (muscles of larynx,
1 muscle of tongue)
• Parasympathetic (thoracic
and abdominal organs)
• Accessory (XI)
– Motor
(sternocleidomastoid,
trapezius)
• Hypoglossal (XII)
– Motor (tongue
and throat
muscles)

23. EXIT POINTS

24. OLFACTORY NERVE
• The olfactory nerve is the shortest cranial nerve and is the
nerve which transmits special sensory information, allowing
us to have a sense of smell.
• It is one of two nerves that do not join with the
brainstem, the other being the optic nerve.
• It is similar to the optic nerve also in its structure, as it has a
meningeal covering unlike CN III to XII.
• Embryologically it is derived from the otic placode (a
thickening of the ectoderm layer)
• The olfactory nerve is also capable of regeneration.
Olfactory nerves are unmyelinated and covered by
Schwann cells.

26. CLINICAL ANATOMY
 Anosmia
-Loss of smell
 Cerebrospinal fluid rhinorrhoea
 Temporal lobe epilepsy

27. OPTIC NERVE
• The optic nerve transmits the special sensory information
for sight. It is one of two nerves that do not join with
the brainstem (the other being the olfactory nerve, CN I).
• Embryologically, the optic nerve is developed from the
optic vesicle, an out-pocketing of the forebrain.
• Due to its unique anatomical relation to the brain, the optic
nerve is surrounded by cranial meninges (not by epi-, peri-
and endoneurium like most other nerves).

30. OCULOMOTOR NERVE
• The oculomotor nerve is the third cranial nerve (CNIII).
• Origin: Midbrain
• Cranial passage: superior orbital fissure
• Innervates :
- Extra-occular muscles :
1.)Superior, Inferior & Medial Recti Muscles
2.)Inferior oblique Muscle
- Also levator palpabre superioris
• Causes the eye to turn upward, downward and medially.
• If this nerve is damaged, the action of the remaining two muscles
(superior oblique and lateral rectus) pulls the eye "down and out” .

31. EDINGER-WESTPHAL NUCLEUS
• Source of the parasympathetics to the eye, which
constrict the pupil and accommodate the lens.
• It is located just inside the oculomotor nuclei.
• The fibers travel in the IIIrd nerve, so damage to that
nerve will also produce a dilated pupil.

33. APPLIED ANATOMY
• Lateral strabismus, as medial rectus is paralysed and the
lateral rectus is unopposed.
• Diplopia, double-vision as one of the eye deviates from the
midline;
• Inability to move the eye medially or vertically;
• Ptosis as the ipsilateral levator palpebrae superioris is
paralysed.
• Mydriasis (dilated pupil of affected side) and
unresponsiveness to light as the sphincter pupillae is non-
functional and the dilator pupillae is unopposed;
• Inability for the affected eye to focus on near objects as the
ciliary muscles have also been paralysed.

34. TROCHLEAR NERVE (IV)
• The trochlear nerve is the fourth paired cranial nerve.
• It is the smallest cranial nerve (by number of axons), yet has the longest
intracranial course
• Origin: Midbrain
• Supplies : Superior oblique muscle.
• Cranial passage : superior orbital fissure
• Its cell bodies are located in the contralateral trochlear nucleus.
• The superior oblique muscle helps to move the eye downward and
medially (inferomedial).
 The trochlear nerve is unique in that:
• It is the only cranial nerve attached to the dorsal aspect of the brainstem
(exits the brainstem dorsally)
• It is the only one to originate completely from the contralateral nucleus
• It is the thinnest and is particularly vulnerable to traumatic injury.

36. APPLIED ANATOMY
• Damage to the trochlear nerve result in much less drastic and noticeable
deficits than damage to the oculomotor or abducens nerves.
• Attempted movements in these directions (e.g., reading or walking down
stairs) may cause diplopia.
• Eye points superolaterally.
• This condition often causes vertical double vision as the weakened muscle
prevents the eyes from moving in the same direction together.
• Bielschowsky's Phenomena :To compensate for the double-vision
resulting from the weakness of the superior oblique, patients
characteristically tilt their head down and to the side opposite the affected
muscle.

37. DIPLOPIA
BIELSCHOWSKY'S
PHENOMENA

38. Examination of the Trochlear Nerve
• The trochlear nerve is examined in conjunction with the
oculomotor and abducens nerves by testing the movements of
eye.
• The patient is asked to follow a point (commonly the tip of a pen)
with their eyes without moving their head. The target is moved in
an ‘H-shape’ and the patient is asked to report any blurring of
vision or diplopia (double vision).

39. TRIGEMINAL NERVE
• The trigeminal nerve, CN V, is the fifth paired cranial nerve.
• It is also the largest cranial nerve.
• The trigeminal nerve is associated with derivatives of the 1st
pharyngeal arch.
• Sensory: The three terminal branches innervate the skin, mucous
membranes and sinuses of the face.
• Motor: Only the mandibular branch of CN V has motor fibres. It
innervates the muscles of mastication: medial pterygoid, lateral
pterygoid, masseter and temporalis. The mandibular nerve also
supplies other 1st pharyngeal arch derivatives: anterior belly of
digastric, tensor veli palatini and tensor tympani.
• Parasympathetic Supply: The post-ganglionic neurons of
parasympathetic ganglia travel with branches of the trigeminal nerve.

41. OPHTHALMIC NERVE - CN ( V1)
• Origin: Anterior aspect of the pons
• Opening to the Skull: Superior orbital fissure
• It has 3 main branches :
* Frontal
* Nasociliary
* Lacrimal

43. OPHTHALMIC DIVISION (V1)

44. MAXILLARY NERVE: CN V2
• Other names : n. maxillaris; superior maxillary nerve
• Origin: Anterior aspect of the pons
• Opening to the Skull: Foramen rotundum
• Compostion: sensory
Infraorbital foreman

47. MANDIBULAR NERVE
• It is the largest of the 3 divisions of trigeminal nerve.
• It is the nerve of the first branchial arch.
• Origin: Anterior aspect of the pons
• Opening to the Skull: Foramen Ovale
• Composition : Mixed nerve.
• It is formed by a large sensory root and a small motor root.
• Both roots join to form the main trunk which lies in the infratemporal
fossa. After a short course the main trunk divides into small anterior
and a large posterior division.

50. DISTRIBUTION OF BRANCHES OF TRIGEMINAL NERVE
TO TEETH AND SURROUNDING STRUCTURES –
MAXILLARY ARCH
TEETH T. PULP GINGIVA PDL &
ALVEOLAR
PROCESS
HARD PALATE
Anteriors Ant .Sup alv
nerve
Palatal- Nasoplalatine
Labial – Infraorbital
& Ant sup Alv nerve
Ant sup
alveolar nerve
Nasopalatine nerve
Premolars Middle sup alv
nerve
Palatal – Ant palatine
nerve
Buccal – Middle sup
alv and infraorbital
nerve
Middle
superior
alveolar nerve
Anterior palatine
nerve
Molars Post sup alv
nerve except
MB root of first
molar
Palatal – Ant palatine
nerve
Buccal – Post sup
alveolar nerve
Post sup
alveolar nerve
Ant palatine nerve
Soft palate –
Middle and post
palatine nerves

51. MANDIBULAR ARCH
Anteriors Incisive branch of
Inferior alv nerve
Lingual – Lingual
N
Labial – Mental N
Incisive N
Premolars Dental branch of
Inferior alv nerve
Lingual – Lingual
N
Buccal – Mental N
Dental branch of
inferior alveolar
nerve
Molars Dental branch of
inferior alveolar
nerve
Lingual – Lingual
N
Buccal –
Buccinator N
Dental branch of
inferior alveolar
nerve
TEETH DENTAL
PULP
GINGIVA PDL & ALV.PRO

52. APPLIED ANATOMY OF TRIGEMINAL
NERVE

53. TRIGEMINAL NEURALGIA
• Trigeminal neuralgia ( tic douloureux ) is a sensory disorder of CN
V that is characterized by sudden attacks of excruciating,
lightening like jabs of facial pain.
• A paraoxysm (sudden sharp pain) can last for 15 mins or more.
• The maxillary nerve is most frequently involved, then the
mandibular nerve, and least frequently the ophthalmic nerve.
• The pain is initiated by touching a sensitive trigger zone of the
skin.
• The cause of trigeminal neuralgia is unknown , but some
investigators believe that it can be due to a anomalous blood vessel
that compresses the nerve.

54. • Etiology-
• Dental etiology
• Infections
• Intracranial tumors
• Intracranial vascular abnormalities
• Viral etiology
• Multiple sclerosis
• Treatment
• Carbamazepine and phenytoin are the traditional anticonvulsants
used .
• Surgical treatment-
• Peripheral injections-long acting anaesthetic agents , alcohol
injections.
• Peripheral neurectomy(nerve avulsion)
• Infraorbital neurectomy.
• Inferior alveolar neurectomy.
• Glycerol injections.

55. Frey’s syndrome:
damage to auriculotemporal nerve & subsequent reinnervation of
sweat glands.
C/F: Flushing & sweating on the invovled side of the face
Treatment: severing the nerve

56. INFRAORBITAL NERVE BLOCK
• For local anesthesia of the inferior part of the face, the
infraorbital nerve is infiltrated with an anesthetic agent. The
site of injection is the infraorbital foramen.
• Careful aspiration is essential as a careless injection may
result in passage of anesthetic fluid into the orbit causing
temporary paralysis of the extraocular muscles.

57. INFERIOR ALVEOLAR NERVE
BLOCK
• Care should be taken during nerve block , if the needle goes
too far posteriorly, it may enter the parotid gland and
anesthetize branches of facial nerve, producing transient
unilateral facial paralysis.

58. NERVE DAMAGE
• Nerve damage ,which occurs almost
exclusively during the removal of lower third
molars has been reported in inferior
alveolar nerve and lingual nerve , less
frequently the long buccal nerve.

59. Inferior alveolar nerve injuries :
• Damage to inferior alveolar nerve occurs primarily
because of the anatomic relationship between the 3rd
molar and nerve.
• IAN enters the mandible at the mandibular foramen and
exists the mandible at the sides of the chin from mental
foramen.

60. Injury to lingual nerve : -
• Lingual nerve is more suspectable to traumatic
injury in 3rd molar region because of its proximity
to the retro molar and paralingual sulcus mucosa.
• Lingual nerve courses just inside the jaw bone,
entering the tongue and supplying sense of
and taste to the right and left half of anterior 2/3
of tongue as well as lingual gingiva.

61. • Injury results in abnormal taste sensation, and
visible fungiform papillae are atrophic on lingual
nerve injured sides of the anterior tongue tip when
compared with normal sides.
• Thus distrophic changes of the fungiform papillae
density of the anterior tongue tip may provide
objective assessment of LN nerve injury in some
patients.

62. CLINICAL EVALUATION OF CN V
• The sensory function is tested by asking the patient to close
his or her eyes and respond when feeling a touch.
• A piece of guaze or test tubes filled with warm and cold
fluid are applied to one cheek and then to the
corresponding position on the other side. The testing is
then repeated with gentle touch of a sharp pin alternating
sides.
• The motor function is tested by asking the
patient to open the mouth against resistance . Action of
both pterygoid muscles keeps the open jaw in the midline.
If pterygoid muscles of one side is paralysed , the jaw is
deviated to the paralysed side ( Pterygoid muscles of one
side pushes the jaw to the opposite side normally ).

63. ABDUCENT NERVE
• Origin : fibres originate from the ipsilateral abducens nuclei located
in the caudal pons beneath the 4th ventricle
• Component: Motor
• Function: Lateral rectus muscle turns eyeball laterally
• Opening to the Skull: Superior orbital fissure
• Supplies : Lateral rectus muscle.
Clinical Significance of the Abducens Nerve (Lateral Gaze)
• This causes medial strabismus (the affected eye deviates medially by
the unopposed action of the medial rectus muscle).
• The individual may be able to move the affected eye to the midline, but
no further, by relaxing the medial rectus muscle.

65. Component: Mixed
Origin : Medulla oblongata
Opening to the Skull: Internal acoustic meatus, facial canal, stylomastoid foramen
 Function:
Motor
o muscles of the face and scalp
o Stapedius muscle
o Posterior belly of digastric
o Stylohyoid muscles
Sensory
o Taste from ant. 2/3 of tongue, from the floor of the mouth and palate
Secretomotor
o Submandibular and sublingual salivary glands
o Lacrimal gland
o Glands of nose and palate
FACIAL NERVE (CN VII)

68. BRANCHES OF FACIAL NERVE
Branches within facial canal :
1. Greater petrosal nerve
2. Nerve to the stapedius
3. Chorda tympani
Branches immediately below the stylomastoid
foramen :
1. Posterior auricular
2. Diagastric
3. Stylohyoid
Branches within the parotid gland :
1. Temporal
2. Zygomatic
3. Buccal
4. Mandibular
5. Cervical

69. APPLIED ANATOMY OF FACIAL
NERVE

70. FACIAL PALSY
• Facial palsy is due to the paralysis of facial nerve.
• It is of 2 types – * Upper motor neuron
type
* Lower motor neuron
type
• .

71. Upper motor neuron lesions
• Lesions above the facial nerve nucleus in the pons, Produces paralysis
of the muscles of the lower half of the face only because the upper
facial muscles are innervated from both the cerebral hemispheres. (the
patient is able to wrinkle the skin of the forehead)
• Lower motor neuron lesions
These include the lesions of the facial nerve nucleus or distal to it. (
ipsilateral facial paralysis )
The site can be determined by testing the function of the branches of
the nerve

73. Bells Palsy:
Idiopathetic unilateral lower motor
neuron paralysis of sudden onset.
Coined by Sir Charles Bell.
A syndrome that consisted of ipsilateral facial paralysis with
intact facial sensation that occurred after the transection of
facial nerve.
slight female predeliction
Etiology: Ischemia, edema and compression of the nerve

74. • Unilateral involvement of the entire side of the face.
• Inability to smile, blink or
wink or raise eyebrows
and whistle.
• Absence of wrinkles on
forehead
• Corner of mouth droops
• Obliteration of the naso-
labial fold.
spontaneous remission occurs
in 85% of the cases.

75. Treatment of bell’s palsy:
• Physiotherapy indicated to maintain muscle tone consisting of
gentle massage & facial exercises.
• Proper care of the eye
-eyedrops/artificial tears
-goggles for dust protection
 Steroids – prednisolone 1mg/kg body wt for 10-14 days with a
gradual tapering.
 Antiviral agents
 Alcohol injections

76. MILLARD GUBULER SYNDROME
• Abducens nerve palsy on the ipsilateral side.
• Infra nuclear type of facial nerve palsy.
• Contra lateral hemiplegia.
Raymond Foville Syndrome
• Paralysis of conjugate occular deviation to same side of lesion.
• Contralateral hemiplegia, infra nucleus facial nerve palsy on
the same side.
Ramsay Hunt Syndrome
• Herpetic eruption in the external acoustic meatus due to the
involvement of facial nerve.
• Facial nerve injured by forceps delivery, fracture of skull,
tumour, middle ear infection.

77. • Injury of Zygomatic branch of CN VII
• Leads to paralysis, loss of tonus of orbicularis oculi, in the lower
eyelid thus the lower eye lid drops.
• As a result, tears do not spread over the cornea and the dry cornea
ulcerates – results in corneal scar – impairs vision.
• Paralysis of Buccal branch
• It prevents the emptying of food from the vestibule of the cheeks.
• The food lodges in the vestibule and cannot be maintained in
position between the teeth for chewing.
• Paralysis of Marginal mandibular branch of CN VII
• This may occur when an incision is made along the inferior border
of the mandible.
• Injury to this branch results in an slightly drooping of the corner of
the mouth.

78. CLINICAL EVALUATION OF FACIA
NERVE
Tested by checking the facial muscles :
1. FRONTALIS: Ask the patient to look upward without moving his
head and look for normal horizontal wrinkles of the forehead.
2. ORBICULARIS OCULI: Tight closure of eyes.
3. ORBICULARIS ORIS: whistling and pursing the mouth.
4. DILATOR OF MOUTH: Showing the teeth.
5. BUCCINATOR: Puffing the mouth and then blowing forcibly.
6. PLATYSMA: Forcible pulling of the angle of the mouth
downwards and backwards forcing vertical folds of skin on the
side of the neck.
• Taste on each half of the anterior two thirds of the
tongue can be tested with sugar, salt, vinegar and
quinine for sweet, salt, sour and bitter sensation.

79. VESTIBULOCOCHLEAR
NERVE
• The vestibulocochlear nerve is the eighth paired cranial nerve. It is
comprised of two parts – vestibular fibres and cochlear fibres.
• Other Names : Auditory / Acoustic Nerve
• Component : Sensory
• Function:
o Vestibular – Saculae/saccule/semicircular canals – Balance
position of head
o Cochlear – Organ of Corti – Hearing
• Origin: Medulla oblongata
• Opening to the Skull: Internal acoustic meatus

80. APPLIED ANATOMY
• Vestibular Neuritis
• Vestibular neuritis refers to inflammation of the vestibular branch of
the vestibulocochlear nerve. The aetiology of this condition is not
fully understood, but some cases are thought to be due to
reactivation of the herpes simplex virus.
• It presents with symptoms of vestibular nerve damage:
• Vertigo – a false sensation that oneself or the surroundings are
spinning or moving.
• Nystagmus – a repetitive, involuntary to-and-fro oscillation of the
eyes.
• Loss of equilibrium.
• Nausea and vomiting.
• The condition is usually self-resolving.
• Treatment is symptomatic, usually in the form of anti-emetics or
vestibular suppressants

81. • Labyrinthitis
• Labyrinthitis refers to inflammation of the membranous
labyrinth, resulting in damage to the vestibular and
cochlear branches of the vestibulocochlear nerve.
• The symptoms are similar to vestibular neuritis, but also
include indicators of cochlear nerve damage:
• hearing loss.
• Tinnitus – a false ringing or buzzing sound.

82. GLOSSOPHARYNGEAL
NERVE
• The glossopharyngeal nerve, CN IX, is the ninth paired cranial nerve
• Embryologically, the glossopharyngeal nerve is associated with the
derivatives of the third pharyngeal arch.
• Other Name : Hering ’s nerve
• Component : Mixed
• Origin: Medulla oblongata
• Opening to the Skull: Jugular foramen
• Function:
• Motor
Stylopharyngeus muscle – assists swallowing
• Sensory
Pharynx
Carotis sinus and carotid body
Gustatory :-
Posterior one third of tongue including circumvallate papillae.
• Secretomotor (parasymphathetic)
Parotid gland

84. APPLIED ANATOMY OF
GLOSSOPHARYNGEAL NERVE

85. • Complete lesion of the glossopharyngeal nerve results in the following :
1. Loss of taste and common sensations over the posterior one third of the
tongue.
2. Difficulty in swallowing
3. Loss of salivation from the parotid gland
4. Unilateral loss of gag reflex
Complete lesion of glossopharyngeal nerve is rare in isolation. There is often
involvement of vagus nerve.
Glossopharyngeal Neuralgia
• It is known as tic douloureux of CN IX or Cranial mononeuropathy IX .
• It is a condition in which there are repeated episodes of severe pain in the
tongue, throat, ear and tonsils which can last from few seconds to few minutes.
• It is believed to be caused by irritation of the ninth cranial nerve. The sudden
intensification of pain is of a burning or stabbing nature.
• Paroxysms of pain are initiated by swallowing, protruding the tongue, talking or
touching the palatine tonsil.
• Pain paroxysms occur during eating when trigger areas are stimulated.

86. • Clinical Relevance – Gag Reflex
• The glossopharyngeal nerve supplies sensory innervation to
the oropharynx, and thus carries the afferent information for
the gag reflex. When a foreign object touches the back of
mouth, this stimulates CNIX, beginning the reflex. The
nerve in this process is the vagus nerve, CNX.
• An absent gag reflex signifies damage to the
glossopharyngeal nerve.

87. VAGUS NERVE
• The vagus nerve is the 10th cranial nerve (CN X).
• The vagus nerve is associated with the derivatives of the fourth
pharyngeal arch.
• Vagus nerve is a mixed nerve.
• Containing approximately 80% sensory fibers.
• It supplies :
Organs of voice and respiration with both motor and sensory fibres
.
 Pharynx (except stylopharyngeus), oesophagus, stomach and heart
with motor fibres.
One muscle of the tongue (palatoglossus).
The muscles of the soft palate (except tensor veli palatini ).
• It is the most extensive cranial nerve, consisting of many branches.

89. CLINICALANATOMY OF VAGUS
NERVE
• Lesion Of Vagus Nerve Leads To :
Dysphagia
Hoarseness
Uvula points away from the affected side
 Loss of gag and cough reflex

90. APPLIED ANATOMY
• Recurrent laryngeal nerve palsies are most common due to
malignant disease (25%) and surgical damage (20%) during
operation of thyroid gland,neck, esophagus,heart,lungs.
• Because of its longer course, lesion of left are more
frequent than those of right.
• High lesions of the vagus nerve, which affect the
pharyngeal and superior laryngeal branches causes
difficulty in swallowing as well as vocal cord defects.

91. ACCESSORY NERVE
• The accessory nerve is the eleventh paired cranial nerve.
• Component: Motor
• Function:
 Cranial root
o Muscles of soft palate (except tensor veli palatini)
o Muscles pharynx (except styopharyngeus)
o Muscles of larynx (except cricothyroid)
 Spinal root
o Sternocleidomastoid
o Trapezius muscle
• Origin: Medulla oblongata
• Opening to the Skull: Jugular foramen

93. ASSESSING X & XI CRANIAL NERVES
• CN X &XI can be assessed together by testing the gag
reflex, palatal movement and sensation.
• Touching the pharynx with an orange stick tests pharyngeal
sensation (9th nerve) and the gag reflex (9th and 10th
nerve). On phonation the soft palate should rise
symmetrically in the midline (10th nerve).
• CN XI can be tested by assessing the power of the
sternocleidomastoid and the trapezius muscles i.e.
turning the head and shrugging the shoulders.

94. APPLIED ANATOMY OF
ACCESSARY NERVE
• Lesion may result the followings :
Shoulder droop
Weakness turning head to opposite side
Palsy of the Accessory Nerve
• The most common cause of accessory nerve damage is iatrogenic
(i.e. due to a medical procedure). In particular, operations such as
cervical lymph node biopsy or cannulation of the internal
jugular vein can cause trauma to the nerve.
• Clinical features include muscle wasting and partial paralysis of the
sternocleidomastoid, resulting in the inability to rotate the head or
weakness in shrugging the shoulders. Damage to the muscles may
also result in an asymmetrical neckline

95. HYPOGLOSSAL NERVE
• The hypoglossal nerve is the twelfth paired cranial nerve.
• Its name is derived from ancient Greek, ‘hypo‘ meaning under, and
‘glossal‘ meaning tongue.
• Component : Motor.
• Supplies : Muscles of the tongue except the palatoglossus.
• Fibers arises : From the hypoglossal Nucleus which lies in the
Medulla, in the floor of the fourth verticle deep to hypoglossus
triangle.
• Opening to the skull : Hypoglossal canal.

98. MOTOR FUNCTION
• The hypoglossal nerve is responsible for motor innervation of the vast
majority of the muscles of the tongue (except for palatoglossus). These
muscles can be subdivided into two groups:
• i) Extrinsic muscles
• Genioglossus (makes up the bulk of the tongue)
• Hyoglossus
• Styloglossus
• Palatoglossus (innervated by vagus nerve)
• ii) Intrinsic muscles
• Superior longitudinal
• Inferior longitudinal
• Transverse
• Vertical
• Together, these muscles are responsible for all movements of the
tongue.

99. APPLIED ANATOMY OF HYPOGLOSSAL
NERVE

100. INJURY TO THE HYPOGLOSSAL
NERVE
• The hypoglossal nerve
accompanies the tonsillar artery
on the lateral wall of the pharynx
and this wall is vulnerable to injury
during tonsillectomy.
• Injury to CN twelve paralyses the
ipsilateral half of the tongue. After
some time the tongue atrophies,
making it appear shrunken and
wrinkled.

101. PALSY OF THE
HYPOGLOSSAL NERVE
• Damage to the hypoglossal nerve is a relatively uncommon
cranial nerve palsy. Possible causes include tumours and
penetrating traumatic injuries. If the symptoms are accompanied
by acute pain, a possible cause may be dissection of the
internal carotid artery.
• Patients will present with deviation of the tongue towards the
damaged side on protrusion, as well as possible muscle wasting
and fasciculations (twitching of isolated groups of muscle fibres)
on the affected side.

102. EXAMINATION OF THE
HYPOGLOSSAL NERVE
• The hypoglossal nerve is examined by asking the patient to
protrude their tongue.
• Other movements such as asking the patient to push their
tongue against their cheek and feeling for the pressure on
the opposite side of the cheek may also be used if damage
is suspected.

103. CONCLUSION
• The course of cranial nerves in relation to the oral
maxillofacial structures is important
• This information can help surgeons gain more
understanding of the location of the nerves and perform
safe surgeries in maxilla as well as the mandible.

105. REFERENCES
• Grays anatomy 39th edition
• Last’s anatomy regional and applied pain-10th Edition
• B D Chaurasia - Textbook of Human’s Anatomy – 5th
Edition
• Inderbir Singh - Textbook of Anatomy – 8th Edition
• Monheim’s local anesthesia & pain control in dental
practice.7th edition.
• Last’s anatomy regional and applied pain-10th Edition

106. THANK YOU